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OBDII Computer in a NON OBDII Car
Topic Started: May 3 2011, 11:08 PM (1,945 Views)
nerys
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Grr

OK I want to use something like a scangauge or ultra gauge.

but I have a 94 NON OBDII metro.

would it be possible to "wire up" just enough of a OBD II computer to get one of those gadgets to work?

errors and stuff won't matter. just the minimum needed to get a MPG reading.

I am guessing lines to the fuel injector and what else?

IE wire in the ability of sensors to SEND data to the 96+ computer but NOT for it to be able to send any commands back to my car IE "read only" so to speak.

is it remotely possible? what is the minimum I would need to hook up to get it to read out my fuel economy to something like a scangauge or ultra gauge?
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MPGuino. Google it. 4 wires.
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mcmancuso
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mpguino= cheaper, easier, more accurate.
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mcmancuso
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nerys
May 3 2011, 11:08 PM
I am guessing lines to the fuel injector and what else?
OBD2 does not monitor fuel injector pulse, ultragauge and SG2 infer MPG via engine load and other factors.
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wizard93
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I would think that the OBD II system would require a downstream O2 sensor, at least an emulator. Not sure what else is required.
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mcmancuso
May 3 2011, 11:18 PM
nerys
May 3 2011, 11:08 PM
I am guessing lines to the fuel injector and what else?
OBD2 does not monitor fuel injector pulse, ultragauge and SG2 infer MPG via engine load and other factors.
Power, ground, VSS, and fuel injector.

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nerys
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Grr

hmm did not realize the guino was so simple and it more accurate?
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nerys
May 4 2011, 01:25 AM
hmm did not realize the guino was so simple and it more accurate?
It is indeed simple. However, you will construct one yourself, or purchase (donate) for one that is pre-assembled. The pre-assembled does not have an enclosure.

I would think that it would be very precise, once calibrated. It counts VSS pulses (miles/speed), and counts the number of times the FI circuit closes (gallons).

VSS signals are used to display RPMs and MPHs. You won't need a tachometer if you don't already have one. You can forget about looking at your speedometer. The MPGuino will give you the most accurate information. Use a GPS with a trip log for calibration of the device.

I'm going to get one for my '90 model.

Otherwise, you can convert your car to an ODBII system . . . :'( :D
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maxmpg
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Take it from a guy who's gone the extra mile for glory, but ended up doing three times the work for a half-assed solution...and in the end just did the simple fix....

go MPGuino if you want it to Just Work(tm) ^o)
go OBDII if you want to bang your head on the hood for hours on end and diagnose unnecessary ghosts in the machine... :banghead :banghead :banghead :banghead :smackface

(I have not done either, but will be buying an MPGuino soon)
Edited by maxmpg, May 4 2011, 07:47 AM.
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bogs
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Duct tape heals all wounds

Geo Glenn
May 4 2011, 06:35 AM
I would think that it would be very precise, once calibrated. It counts VSS pulses (miles/speed), and counts the number of times the FI circuit closes (gallons).
This is correct.
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VSS signals are used to display RPMs and MPHs. You won't need a tachometer if you don't already have one. You can forget about looking at your speedometer. The MPGuino will give you the most accurate information. Use a GPS with a trip log for calibration of the device.
The parts in bold are not, Mpguino does not have an rpm function (they were looking at it, I do not think it was ever implemented). It would not work off the vss in any case (vehicle speed sensor), that is only used to determine your speed. I believe they were *thinking* of using the f.i. wire to test for rpms, but again it did not get implemented.
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Otherwise, you can convert your car to an ODBII system . . . :'( :D
And that is exactly what you would have to do to use an ultra-gauge or sg2, your not going to be able to get it to work by running the various wires to different components, because the obd2 gauges themselves don't work like that, they work by interpreting the iso standard information provided to the obd2 port. The only part of those 2 devices that would work by running a wire somewhere is the power and ground.
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mcmancuso
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It does have the RPM function in the program, but you have to enable it. I think you can only do this by re-flashing the chip in the most recent version. I believe it was left out because its keyed off the injector pulse, and the injector pulse stops in many circumstances: EOC, DFCO, etc...
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:gp

Ohhhhhhh! :shake Maybe me's be reconsidering the Arduino DIY options. No tachulation? Suzuki Steve had me confused with his project. The DIY Arduino guys have figured out how to do RPM's

Hey, we're talking with nerys here! :D Give the man a schematic, and he'll move the electrons, as required!
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mcmancuso
May 4 2011, 09:49 AM
It does have the RPM function in the program, but you have to enable it. I think you can only do this by re-flashing the chip in the most recent version. I believe it was left out because its keyed off the injector pulse, and the injector pulse stops in many circumstances: EOC, DFCO, etc...
Wait, there is a hack! Mcmancuso knows! Yes, there is hope through hacking. :thumb
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nerys
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Grr

think I am going to save up for a guino. they are only $60 IIRC a lot cheaper than SG's etc.. I just thought they were an ultra pain to hook up :-)
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mcmancuso
May 4 2011, 09:49 AM
It does have the RPM function in the program, but you have to enable it. I think you can only do this by re-flashing the chip in the most recent version. I believe it was left out because its keyed off the injector pulse, and the injector pulse stops in many circumstances: EOC, DFCO, etc...
It would make more sense to run the RPM function off the VSS. Go figure. :'(
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